1. Field of the Invention
The invention relates to a grommet that can be assembled onto a wiring harness and mounted in a through hole formed in a body panel of an automotive vehicle. The grommet protects the wiring harness and makes a portion where the wiring harness is introduced into the through hole waterproof and dustproof.
2. Description of the Related Art
A grommet typically is mounted on a wiring harness that will extend from an engine compartment to a passenger compartment of an automotive vehicle. The grommet and the wiring harness then are mounted in a through hole of a body panel that partitions the engine compartment from the passenger compartment. Accordingly, the grommet protects the wiring harness at the through hole and prevents the flow of water, dust and sound from the engine compartment to the passenger compartment.
A grommet of the type described above is referred to as a xe2x80x9cone-motion grommetxe2x80x9d and has a body-locking recess around its outer periphery. The body locking recess is configured for engagement with the surrounding edge of a through hole of a body panel merely by pushing the grommet into the through hole in one direction. A one-motion grommet has the potential for easy mounting.
A known one-motion grommet is disclosed in Japanese Unexamined Utility Model Publication No. 4-40823 and also is identified by the numeral 1 in FIG. 4 herein. The grommet 1 is formed with a small diameter tube 2 that is continuous with a large-diameter tube 3. A bundle of wires W is introduced through the small diameter tube 2, and closely contacts the inner surface of the small diameter tube 2. A stepped thick portion 4 is formed on the outer circumferential surface of the large-diameter tube 3, and a body locking recess 5 is formed in the outer circumferential surface of the stepped thick portion 4. Finally, a slit 6 is formed in the thick portion 4 and an annular metallic core 7 is pressed into the slit 6.
The grommet 1 is pushed in the direction of arrow Q from an engine compartment (X) to a passenger compartment (Y) without the annular metallic core 7 in the slit 6. More particularly, a slanted surface 5a adjacent the body locking recess 5 engages an edge of a body panel 8 that surrounds a through hole 9 formed in the body panel 8. As a result, the stepped thick portion 4 is deformed inwardly into the cut-away portion 6 of the grommet 1. Further pushing enables the slanted surface 5a to pass through the through hole 9 in the body panel 8. The stepped thick portion 4 is restored to its original shape after passing through the through hole 9, so that the body panel 8 is locked in the body locking recess 5. The annular metallic core 7 is pressed into the slit 6 after the body panel 8 is engaged in the body locking recess 5 to prevent the grommet 1 from coming off into the engine compartment X.
The thick portion 4 in which the body locking recess 5 is formed has a low elastic locking force. Thus, the separate annular metallic core 7 is required to prevent the grommet 1 from coming off into the engine compartment X. However, the need to assemble the grommet 1 and the annular metallic core 7 requires an additional operation step after the grommet 1 is mounted.
Further, the large-diameter portion 3 is spaced outward from the wiring harness W to facilitate inward elastic deformation of the stepped thick portion 4 at the insertion side of the body locking recess 5 when the grommet 1 is mounted into the through hole. Thus, the through hole 9 in the body panel 8 must be larger than the outer diameter of the wire bundle W. However, it is preferable to minimize the size of the through hole 9 in the body panel 8 for soundproofing purposes.
In view of the above problems, an object of the invention is to enable a grommet to be firmly and easily mounted on a body panel without using a separate member.
Another object of the invention is to enable a small through hole in the body panel.
The invention is directed to a grommet that can be mounted on a wiring harness and inserted in an insertion direction into a through hole of a panel. The grommet may be formed integrally or unitarily of a rubber or elastomer and is configured for engaging portions of the panel adjacent the through hole.
The grommet includes a small-diameter tube with opposite front and rear ends and an inner circumferential surface extending between the ends. The inner circumferential surface of the small diameter tube is dimensioned to receive and closely engage a bundle of wires. A jaw projects in a fold-back direction from the outer circumference of the front end of the small-diameter tube, and a body locking recess is formed in the jaw. The jaw comprises at least one thinned wall that allows a substantially radial movement of the jaw towards the small-diameter tube upon insertion of the grommet into the through hole. The thinned wall facilitates deflection of the jaw so that the grommet can be inserted easily and firmly into the through hole of the panel.
The jaw preferably has a slanted outer surface that gradually increases its outer diameter toward the back. The body locking recess preferably is formed in or adjacent the slanted outer surface of the jaw. The inner circumferential surface of the jaw and the outer circumferential surface of the small-diameter tube meet substantially at a base end of the slanted surface of the jaw, thereby thinning the base end.
The jaw is folded back and outwardly from the front end of the small-diameter tube, and thus a forward-acting elastic force is provided to the jaw. The body locking recess in the outer circumferential surface of the jaw firmly engages the body panel, and thus the grommet does not come off the body panel and into the engine compartment. Consequently, there is no need for the metallic core that is required to prevent the prior art grommet from coming off the body panel.
A large annular clearance is defined between the jaw and the small diameter tube at the time of mounting the grommet onto the body panel. The outer circumferential surface of the small-diameter tube is slanted outwardly so that the annular clearance is tapered toward its front end. Additionally, the front end of the clearance is more forward than the body locking recess. These relative dispositions effectively thin a portion of the jaw at the front end of the clearance. The thinned wall portion preferably is at a radial position that corresponds substantially to the edge of the through hole of the panel. As a result, the jaw is easily deformable about the thinned portion, and the slanted surface adjacent and forward of the body locking recess can easily pass the through hole. Thus, unlike the prior art, the jaw is easily deformable, and the tube through which the bundle of wires is introduced need not have a large-diameter. Rather, it is sufficient to provide the jaw folded back from the leading end of the small-diameter tube through which the wires extend.
The inner circumferential surface of the front side of the small-diameter tube preferably is slanted and gradually increases its diameter toward the front end. Thus, an inner clearance between the bundle of wires and the front side of the small-diameter tube gradually increases. The small diameter tube is easily deformable because of the inner clearance at the front of the grommet and because the portion of the small-diameter tube that is continuous with the jaw is thin. Thus, the force required to insert the grommet is reduced. Further, the inner clearance advantageously enables changes to the direction of the bundle of wires coming out from the small-diameter tube.
An outer diameter of at least part of a circumferential extension of a bottom portion of the body locking recess is slightly larger than an inner diameter of the through hole of the panel. Thus a sealing and/or holding function of the grommet can be enhanced.
These and other objects, features and advantages of the present invention will become apparent upon reading of the following detailed description of preferred embodiments and accompanying drawings.